APT Research Private Limited Data Analytics Interview Questions, Process, and Tips

Round duration - 90 Minutes
Round difficulty - Medium

The round was of 90 minutes.
The first section had 3 coding questions. (leetcode mediums)
The second section had problems based on probability and linear algebra and general mathematics.
The third section had MCQs based on some puzzles and cs fundamentals.

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
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Ans. 
Given an array and a target sum, find pairs of elements that add up to the target sum.
• Iterate through the array and for each element, check if the complement (target sum - current element) exists in a hash set.

• If the complement exists, add the pair to the result list.

• Sort the result list based on the first element of each pair, and then the second element if the first elements are equal.
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Q2. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find the minimum time required to rot all fresh oranges in a grid.
• Iterate through the grid to find rotten oranges and their adjacent fresh oranges.

• Use BFS or DFS to simulate the rotting process and track the time taken.

• Return the minimum time taken to rot all fresh oranges or -1 if not possible.
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Q3. 
Longest Common Prefix Problem Statement
You are given an array ‘ARR’ consisting of ‘N’ strings. Your task is to find the longest common prefix among all these strings. If there is no common prefix, you ha...read more
Ans. 
Find the longest common prefix among an array of strings.
• Iterate through the characters of the first string and compare with corresponding characters of other strings.

• Stop when a mismatch is found or when reaching the end of the shortest string.

• Return the prefix found so far as the longest common prefix.
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Round duration - 45 Minutes
Round difficulty - Easy

This round started with a brief discussion about my projects and previous internship(about 15 mins).
Then it was followed by 2 coding questions(10-12 mins for the first question and 15 mins for the second question).
The interviewer asked me if I had any questions. I asked 2-3 questions about the projects we will be working on the what exactly the company does.

Q1. 
K-th Largest Number in a BST
Given a binary search tree (BST) consisting of integers and containing 'N' nodes, your task is to find and return the K-th largest element in this BST.
If there is no K-th la...read more
Ans. 
Find the K-th largest element in a binary search tree.
• Perform an in-order traversal of the BST to get elements in ascending order

• Return the (N-K)th element from the end of the in-order traversal

• Handle cases where K is out of bounds or no K-th largest element exists
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Q2. 
Peak Element Finder
For a given array of integers arr, identify the peak element. A peak element is an element that is greater than its neighboring elements. Specifically, if arr[i] is the peak, then both...read more
Ans. 
Find the peak element in an array of integers.
• Iterate through the array and check if the current element is greater than its neighbors.

• Handle edge cases where the first or last element can be a peak.

• Return the peak element found.
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Round duration - 70 Minutes
Round difficulty - Easy

It was a mix of HR+technical round. A senior person from the company took my interview. He first asked me about my interests and why I want to join this company and about my future goals. He then asked my favourite topic, and I said graphs. Then we had a good discussion on graphs and the different concepts and popular algorithms. Then he asked 2 coding questions, one related to graphs and one related to backtracking.
After this, we had a brief discussion of some of my ML projects.

Q1. 
Evaluate Division Problem Statement
Given an array of pairs of strings equations representing a fraction and an array of real numbers values. Each element in equations denotes a fraction with the first st...read more
Ans. 
Evaluate division problem statement with given fractions and values to calculate the value of a given fraction.
• Use a graph data structure to represent the fractions and values.

• Perform depth-first search (DFS) to find the value of the given fraction.

• Multiply the values of the fractions along the path from numerator to denominator to get the final result.
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Q2. 
Lexicographically Smallest Array Problem Statement
You are given an array ARR of 'N' integers and a positive integer 'K'.
Your task is to determine the lexicographically smallest array that can be obtain...read more
Ans. 
The task is to determine the lexicographically smallest array that can be obtained by performing at most 'K' swaps of consecutive elements.
• Iterate through the array and swap elements to make the array lexicographically smallest.

• Keep track of the number of swaps made and stop when the limit 'K' is reached.

• Use a sorting algorithm to find the lexicographically smallest array after at most 'K' swaps.
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